In vivo measurement of circulating leucocyte activation in patients following cardiopulmonary bypass

Micro-autoradiographic assessment of cell types contributing to 2-deoxy-2-[(18)F]fluoro-D-glucose uptake during ventilator-induced and endotoxemic lung injury

PURPOSE

The aim of the study was to use micro-autoradiography to investigate the lung cell types responsible for 2-deoxy-2-[(18)F]fluoro-D-glucose (FDG) uptake in murine models of acute lung injury (ALI).

PROCEDURES

C57/BL6 mice were studied in three groups: controls, ventilator-induced lung injury (VILI), and endotoxin. VILI was produced by high tidal volumes and zero end-expiratory pressure and endotoxin ALI, by intranasal administration. Following FDG injection, the lungs were processed and exposed to autoradiographic emulsion. Grain density over cells was used to quantify FDG uptake.

RESULTS

Neutrophils, macrophages, and type 2 epithelial cells presented higher grain densities during VILI and endotoxin ALI than controls. Remarkably, cell grain density in specific cell types was dependent on the injury mechanism. Whereas macrophages showed high grain densities during endotoxin ALI, similar to those exhibited by neutrophils, type 2 epithelial cells demonstrated the second highest grain density (with neutrophils as the highest) during VILI.

CONCLUSIONS

In murine models of VILI and endotoxin ALI, FDG uptake occurs not only in neutrophils but also in macrophages and type 2 epithelial cells. FDG uptake by individual cell types depends on the mechanism underlying ALI.

Assessment of pulmonary neutrophilic inflammation in emphysema by quantitative positron emission tomography

RATIONALE

Neutrophilic inflammation is understood to be of pathogenetic importance in chronic obstructive pulmonary disease (COPD) and may be quantified using 18-fluorodeoxyglucose positron emission tomography-computed tomography ((18)FDG PET-CT) as a noninvasive, spatially informative biomarker.

OBJECTIVES

To assess the potential usefulness of (18)FDG PET-CT as a surrogate measure of pulmonary neutrophilic inflammation in patients with usual COPD and α(1)-antitrypsin deficiency (AATD).

METHODS

(18)FDG PET-CT imaging was performed in 10 patients with usual COPD, 10 patients with AATD, and 10 healthy control subjects. Pulmonary (18)FDG uptake was estimated by three-dimensional Patlak graphical analysis as an indicator of pulmonary neutrophilic glycolytic activity. Patients with AATD were treated with 12 weekly intravenous infusions of AAT augmentation therapy before repeat imaging. (18)FDG uptake, lung physiology, lung density, and systemic markers of inflammation were compared for all groups at baseline and, in patients with AATD, at baseline and on treatment.

MEASUREMENTS AND MAIN RESULTS

(18)FDG uptake in the upper lung of patients with usual COPD was greater compared with the healthy control group (P = 0.009) and correlated with measures of disease severity (FEV(1)% predicted, r = -0.848, P = 0.001; FEV(1)/FVC, r = -0.918, P < 0.001; Kco% predicted, r = -0.624, P = 0.027; 15th percentile point, r = -0.709, P = 0.011). No significant difference was observed between measurements at baseline and on treatment in patients with AATD.

CONCLUSIONS

Quantitative (18)FDG PET-CT has a potential role as an imaging biomarker in mechanistic and interventional studies in patients with usual COPD. The data support previous evidence of distinct functional characteristics of neutrophils in COPD. Clinical trial registered with https://eudract.ema.europa.eu/index.html (EudraCT 2007-004869-18).

[The influence of cardiopulmonary bypass operation on the biodistribution of 99mTc-HMPAO-labelled granulocytes - Evaluation in pigs by planar scintigraphy and section-analyses]

AIM

of the study was to evaluate the influence of an extra corporal perfusion (cardiopulmonary bypass operation - cpb) on activation and biodistribution of (99m)Tc labelled granulocytes in pigs with and without inhibition of the granulocytes by a leukocyte inhibition module (LIM). The cpb is often related to an activation of granulocytes resulting in an inflammatory answer. The biological mechanisms are unsolved yet. First trials of our group showed that LIM may inhibit the activation of neutrophils and therefore antagonize a cpb-caused impairment of cardiac function. This study is the continuation of these experiments with a higher number of animals and the focus on scintigraphic imaging. ANIMALS, MATERIAL, METHODS: 39 German landrace pigs were subdivided into three groups: group A (control) median sternotomy without cpb, group B with cpb, group C with LIM in addition to cpb. After labelling with (99m)Tc-HMPAO autologues granulocytes were reinjected. Subsequently to cpb, the animals underwent scintigraphic imaging. Quantification was performed with ROI evaluation and with tissue samples (section analysis) examined in a well counter.

RESULTS

A high uptake of (99m)Tc-HMPAO was found in the liver. The count rates in brain, heart, lung, spleen and kidneys were far below. The amount of 99mTc-activity in the organ related to the half life corrected administered activity [%] was for the tissue samples (group A/B/C): brain 0.01/0.02/0.03; lung 12.1/8.3/11.5; heart 0.35/0.54/0.42; kidney 1.24/0.87/1.02; spleen 4.0/4.0/4.5, liver 16.8/20.9/19.6. The count rates determined by ROI-evaluation of the scintigraphic images related to the total count rate in the image [%] were (group A/B/C): brain 1.1/0.9/1.0; lung 15.6/10.4/12.2; heart 4.0/3.5/3.4; kidney 4.0/2.9/3.2; spleen 7.6/7.7/9.5, liver 23.1/36.7/31.4. A significant difference in the tracer uptake between the groups could neither be detected by scintigraphic imaging nor evaluation of tissue samples.

CONCLUSION

Scintigraphic imaging as well as section analysis showed a comparable biodistribution of the tracer. Therefore, the initial results of our group were not confirmed with a considerably higher number of animals. Neither cpb nor the use of the LIM influenced distribution of 99mTc-labelled granulocytes in pigs significantly.